Anyone know what's involved in flairing the rear quarters to WB width? Has anyone done this?

 

I would imagine you buy new factory rear 1/4 panels. Easy.

then....get out the torch and start cutting into your car...replace with new panels, wield. Prep, new bumper, paint, Done.

The Porsche Workshop manuals are a good place to start, they document the removal and replacement of the rear 1/4 panel sheet metal...